1. Field of the Invention
The present invention relates to a stripline PCB dipole antenna, and more particularly to a dual-fed co-planar stripline PCB dipole antenna used in an electronic device for receiving and/or transmitting electromagnetic signals.
2. Related Art
In the communications field, dipole antennas have been widely used for a long time for effectively receiving and transmitting electromagnetic signals. Most electronic devices use single dipole antennas. Conventionally, a single dipole antenna has three radiation planes, namely an XY-plane, an XZ-plane and a YZ-plane. Generally, only one of these radiation planes has preferred radiation efficiency, and the other radiation planes are disregarded. Moreover, a feeding device of a conventional single dipole antenna is complex and occupies a lot of space.
An antenna disclosed in U.S. Pat. No. 4,605,931 utilizes a crossover feeding system. The system comprises pairs of a first feeder apparatus and a second feeder apparatus, one feeder apparatus crossing over the other. Each pair of the crossed first and second feeder apparatuses has a first port and a second port for transmitting a first signal therebetween, and a third port and a fourth port for transmitting a second signal therebetween. The system reduces interaction between signals, and eliminates back feeding of signals. However, the system is too complex to be practically implemented.
Taiwan Patent Application No. 87112281 discloses a circular polarized microstrip antenna that has a short adjustable metal microchip on an edge of a fixed metal microchip. A feed point of the microstrip antenna is on the short adjustable metal microchip or a cross-line thereof which is oriented at 45xc2x0. The metal microchip is installed on a grounding plane. The microstrip antenna has preferred radiation efficiency in the XZ-plane and the YZ-plane. However, the microstrip antenna is also very complex. It requires a large space, and cannot be easily integrated into communications equipment.
Other antennas are disclosed in U.S. Pats. Nos. 4,069,483 and 6,091,366. They all utilize only one of the three radiation planes to provide radiation efficiency.
An object of the present invention is to provide a stripline PCB dipole antenna capable of switching between two of the three radiation planes, namely the XY-plane, the XZ-plane and the YZ-plane, to achieve optimum diversity reception efficiency.
Another object of the present invention is to provide a stripline PCB dipole antenna which reduces any adverse influences that wiring paths of feeder RF cables may have on the characteristics of the antenna.
A further object of the present invention is to provide a feeding method whereby two dipole antennas are fed through feed patches to make full use of two of the three radiation planes and thereby provide optimum diversity reception efficiency.
To achieve the above-mentioned objects, a stripline PCB dipole antenna in accordance with the present invention for placing in an electronic device includes a substrate, a T-shaped first dipole antenna disposed on a surface of the substrate, a T-shaped second dipole antenna disposed on an opposite surface of the substrate and perpendicular to the first dipole antenna, and first and second feeder apparatuses feeding the antennas near respective edges of the substrate. The positioning of the feeder apparatuses reduces any adverse influences that the wiring paths of the feeder apparatuses may have on the characteristics of the stripline PCB dipole antenna.
The stripline PCB dipole antenna utilizes a switch mechanism of dual polarized radiation to switch between two of the three radiation planes, namely the XY-plane, the XZ-plane and the YZ-plane. The stripline PCB dipole antenna thus achieves optimum diversity reception efficiency under the control of an external device.
These and additional objects, features and advantages of the present invention will become apparent after reading the following detailed description of a preferred embodiment of the invention taken in conjunction with the appended drawings.